Internal combustion engines such as diesel engines, gasoline engines, and gaseous fuel powered engines use injectors to introduce fuel into the combustion chambers of the engine. These injectors may be hydraulically or mechanically actuated with mechanical, hydraulic, or electrical control of fuel delivery. One example of a mechanically-actuated, electronically-controlled fuel injector is described in U.S. Pat. No. 6,856,222 (the '222 patent) issued to Forck on Feb. 15, 2005.
The '222 patent describes a fuel injector having a spring-biased, solenoid-controlled spill valve and a spring-biased, solenoid-controlled direct operating check valve (DOC valve). Both the spill valve and the DOC valve are associated with a cam-driven plunger and a control chamber of a valve needle. As the plunger is initially forced by a cam into a bore within the fuel injector, fuel from within the bore flows past the spill valve to a low pressure drain. When the spill valve is electrically closed during further movement of the plunger into the bore, pressure within the bore builds. When an injection of fuel is desired, the DOC valve is electronically moved to connect the control chamber to the low pressure drain, thus permitting movement of the valve needle away from a seating to commence injection. To end injection, the DOC valve disconnects the control chamber from the low pressure drain to return the valve needle to its seating. The time during which the valve needle is away from its seating determines the quantity of fuel injected.
Although the injector of the '222 patent may sufficiently inject fuel into the combustion chambers of an engine, it may lack a damage protection protocol. In particular, following the closing of the spill valve during the downward displacement of the cam-driven plunger, if the DOC valve does not properly close to initiate injection, the rising pressure of the fuel within the injector could reach levels sufficient to damage the injector.
The control system of the present disclosure solves one or more of the problems set forth above.